Introduction

Enermax has recently released two high-efficiency power supply series, MODU82+ and PRO82+. The name implies that products from these two series have efficiency of at least 82%, but Enermax says they actually have efficiency of at least 84%. Both use the same internal project, with MODU82+ models using a modular cabling system. Today we are going to take an in-depth look at the 525 W model from the PRO82+ series (also known as EPR525AWT) and see if it can really deliver its labeled power and efficiency. Read on.

click to enlargeFigure 1: Enermax PRO82+ 525 W power supply.

click to enlargeFigure 2: Enermax PRO82+ 525 W power supply.

As you can see, this power supply uses a big 120 mm ball bearing fan on its bottom (the power supply is upside down on Figures 1 and 2) and a big mesh on the rear side where traditionally we have an 80 mm fan. We like this design as it provides not only a better airflow but the power supply produces less noise, as the fan can rotate at a lower speed in order to produce the same airflow as an 80 mm fan.

This power supply has active PFC, which provides a better usage of the power grid and allowing Enermax to sell this product in Europe (read more about PFC on our Power Supply Tutorial). As mentioned, Enermax says that this product has at least 84% efficiency. Of course we will measure this to see if what the manufacturer claim is true. The higher the efficiency the better – an 80% efficiency means that 80% of the power pulled from the power grid will be converted in power on the power supply outputs and only 20% will be wasted. This translates into less consumption from the power grid (as less power needs to be pulled in order to generate the same amount of power on its outputs), meaning lower electricity bills.

The main motherboard cable uses a 24-pin connector (no support for 20-pin motherboards) and this power supply has two ATX12V connectors that together form an EPS12V connector.

This power supply comes with seven peripheral power cables: three auxiliary power cables for video cards – two of them with 6/8-pin connectors –, two cables containing three standard peripheral power connectors – one of them with a floppy disk drive connector attached –, one cable with three SATA power connectors and one cable with four SATA power connectors.

The number of connectors provided by this power supply is simply amazing for a unit from its power rage. First it provides three (and not just two) video card power cables. Second, it provides seven SATA power plugs, which is more than enough even for extreme high-end users.

This power supply also provides a cable for you to monitor the speed of the power supply fan. This cable should be installed on any empty fan connector on the motherboard and you can monitor the fan speed using your favorite monitoring program.

On this power supply all wires are 18 AWG, which is perfect for a product on this power range.

On the aesthetic side Enermax used nylon sleevings on all cables and they come from inside the power supply housing.

Now let’s take an in-depth look inside this power supply.

A Look Inside The PRO82+ 525 W

We decided to disassemble this power supply to see what it looks like inside, how it is designed, and what components are used. Please read our Anatomy of Switching Power Supplies tutorial to understand how a power supply works and to compare this power supply to others.

This page will be an overview, and then in the following pages we will discuss in detail the quality and ratings of the components used.

The first thing that caught our eye when disassembling this power supply was its 120 mm fan, which uses a 4-pin connector. First we thought it would be a PWM fan, but we got this explanation from Enermax:

“We use a bivoltage fan. We have a patent on this. Normally, when you use a fan, you lower voltage down to 3-4 V, which impacts also the hall IC of any fan, which controls the fan. With such voltage it gets unstable. By using a bivoltage fan (12 V for the hall IC and custom voltage to the bearing – any voltage, way lower than 3) we can go down to 450 rpm (even lower if we would want to). By still having the hall IC powered by 12 V, it can run/control the bearing with its custom voltage more smoothly. That's the difference to any single voltage. But we do use a standard two ball bearing fan, custom manufactured for us. That is what is looking like PWM, but you can see two 12 V wires and no PWM cable. Other manufacturers can match this only by using PWM sleeve bearing fan with limited lifetime. So we are pretty proud of our patented invention and having the world's most silent PSU fan control (and series) without sacrificing on heat or cheating even with sleeve bearing.”

Transient Filtering Stage

As we have mentioned in other articles and reviews, the first place we look when opening a power supply for a hint about its quality, is its filtering stage. The recommended components for this stage are two ferrite coils, two ceramic capacitors (Y capacitors, usually blue), one metalized polyester capacitor (X capacitor), and one MOV (Metal-Oxide Varistor). Very low-end power supplies use fewer components, usually removing the MOV and the first coil.

On this stage this power supply is flawless, providing two extra Y capacitors, one extra ferrite coil and a ferrite bead attached to the main AC cable. This power supply also provides an X capacitor after the rectifying bridge and its MOV is located after the rectifying bridge, not before as usual.

click to enlargeFigure 7: Transient filtering stage (part 1).

click to enlargeFigure 8: Transient filtering stage (part 2).

In the next page we will have a more detailed discussion about the components used in the PRO82+ 525 W.

Primary Analysis

On this page we will take an in-depth look at the primary stage of Enermax PRO82+ 525 W. For a better understanding, please read our Anatomy of Switching Power Supplies tutorial.

This power supply uses one GBU10J rectifying bridge in its primary, which support up to 10 A at 100° C. This bridge is attached to an individual heatsink and is clearly overspec'ed: at 115 V this unit would be able to pull up to 1,150 W from the power grid; assuming 80% efficiency, the bridge would allow this unit to deliver up to 920 W without burning this component. Of course we are only talking about this component and the real limit will depend on all other components from the power supply.

click to enlargeFigure 9: Rectifying bridge.

The active PFC circuit uses two TK20J60T power MOSFET transistors, which one capable of handling up to 20 A in continuous mode or 40 A in pulse mode, both at 25° C. These transistors are located on the same heatsink as the switching transistors.

The primary section of this power supply is controlled by a CM6802B integrated circuit, which is a newer version of CM6800, the most popular active PFC/PWM controller combo around. On this new version the manufacturer guarantees at least 80% efficiency. Nice choice.

click to enlargeFigure 12: Active PFC/PWM controller combo.

Secondary Analysis

This power supply has four Schottky rectifiers on its secondary.

The +12 V output is produced by two SBR40U60PT Schottky rectifiers connected in parallel, each one supporting up to 40 A at 150° C (20 A per internal diode). The maximum theoretical current the +12 V line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by two 20 A diodes in parallel). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 57 A or 684 W for the +12 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +5 V output is produced by one DF40SC4 Schottky rectifier, which supports up to 40 A at 106° C (20 A per internal diode). The maximum theoretical current the +5 V line can deliver is given by the formula I / (1 - D), where D is the duty cycle used and I is the maximum current supported by the rectifying diode (which in this case is made by one 20 A diode). Just as an exercise, we can assume a typical duty cycle of 30%. This would give us a maximum theoretical current of 29 A or 143 W for the +5 V output. The maximum current this line can really deliver will depend on other components, in particular the coil used.

The +3.3 V output is produced by another DF40SC4 Schottky rectifier, which supports up to 40 A at 106° C (20 A per internal diode). So the maximum theoretical power the +3.3 V output can deliver using the above math is of 94 W.

click to enlargeFigure 13: +3.3 V, +12 V and +5 V rectifiers.

This power supply uses a PS231S monitoring integrated circuit, which is in charge of the power supply protections, like OCP (over current protection). Unfortunately there is no datasheet for this component on the manufacturer’s website, so we couldn’t check what protections it really supports. Analyzing the printed circuit board from the reviewed power supply we could clearly see each +12 V virtual rail connected to this integrated circuit.

click to enlargeFigure 14: PS231S monitoring integrated circuit.

The thermal sensor is attached to the secondary heatsink and you can see it in Figure 14 (green component). This sensor is used to control the fan speed according to the power supply internal temperature and to shut down the power supply in an overheating situation, if the power supply implements over temperature protection (OTP). Enermax says that PRO82+ 525 W has this protection set at 95° C, bue we couldn't test this as we couldn't put this power supply to run at such high temperature.

This power supply uses only Japanese electrolytic capacitors, with capacitors from Matsushita (Panasonic) on the active PFC circuit (rated at 85° C) and Chemi-Con on the secondary (rated at 105° C).

Power Distribution

In Figure 15, you can see the power supply label containing all the power specs.

click to enlargeFigure 15: Power supply label.

According to the information present on the product box this power supply is labeled at 40° C.

As you can see this power supply has three +12 V virtual rails, distributed like this:

+12V2 (yellow with blue stripe wires): Two of the power cables for video cards, standard peripheral plugs.

+12V3 (yellow with black stripe wires): The third power cable for video cards, SATA power plugs.

We liked the way power was distributed on this power supply, especially because the CPU (ATX12V/EPS12V connectors) does not share the same rail as any of the video card auxiliary power cables. When this happens the power supply may shut down even if your system is running inside specs, as the over current protection (OCP) may enter in action if you are pulling more than that particular rail can deliver.

Now let’s see if this power supply can really deliver 525 W of power.

Load Tests

First we tested this power supply with five different load patterns, trying to pull around 20%, 40%, 60%, 80%, and 100% of its labeled maximum capacity (actual percentage used listed under “% Max Load”), watching how the reviewed unit behaved under each load. In the table below we list the load patterns we used and the results for each load. Then we tried to pull even more power from this unit and the results for this test is in the next page.

If you add all the power listed for each test, you may find a different value than what is posted under “Total” below. Since each output can vary slightly (e.g., the +5 V output working at +5.10 V), the actual total amount of power being delivered is slightly different than the calculated value. On the “Total” row we are using the real amount of power being delivered, as measured by our load tester.

+12V2 is the second +12V input from our load tester and during our tests we connected the two power supply ATX12V connectors to it. So it was connected to the power supply +12V1 bus. The +12V1 input from our load tester, on the other hand, was connected to both +12V1 (main motherboard connector) and +12V2 (video card and peripheral plugs) rails.

Input

Test 1

Test 2

Test 3

Test 4

Test 5

+12V1

4 A (48 W)

8 A (96 W)

12 A (144 W)

15 A (180 W)

21 A (252 W)

+12V2

4 A (48 W)

8 A (96 W)

11 A (132 W)

15 A (180 W)

16.5 (198 W)

+5V

1 A (5 W)

2 A (10 W)

4 A (20 W)

6 A (30 W)

8 A (40 W)

+3.3 V

1 A (3.3 W)

2 A (6.6 W)

4 A (13.2 W)

6 A (19.8 W)

8 A (26.4 W)

+5VSB

1 A (5 W)

1 A (5 W)

1.5 A (7.5 W)

2 A (10 W)

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

0.5 A (6 W)

Total

118. W

224.5 W

329. W

432.8 W

542.4 W

% Max Load

22.5%

42.8%

62.7%

82.4%

103.3%

Room Temp.

47.3° C

46.8° C

48.4° C

48.4° C

50.0° C

PSU Temp.

51.7° C

51.3° C

51.3° C

51.8° C

53.9° C

Voltage Stability

Pass

Pass

Pass

Pass

Pass

Ripple and Noise

Pass

Pass

Pass

Pass

Pass

AC Power

133 W

249 W

370 W

496 W

635 W

Efficiency

88.7%

90.2%

88.9%

87.3%

85.4%

Final Result

Pass

Pass

Pass

Pass

Pass

What a power supply! It could not only deliver its labeled power at 50° C but it could also maintain efficiency always above 85%, peaking 90% on test number two (40% load, 225 W). This is the first time we’ve seen a power supply peaking more than 90% efficiency. This unit broke our efficiency record set before by Antec EarthWatts 500 W and Corsair VX450W.

Voltage regulation was also outstanding and during all our tests all outputs were within 3% of their nominal voltages – ATX specification defines that all outputs must be within 5% of their nominal voltages (10% for -12 V) –, including -12 V, which usually is not close to its nominal value.

During all tests ripple and noise levels were within specs, but other good mainstream power supplies we’ve reviewed like Antec EarthWatts 500 W and Corsair VX450W achieved far better values on the +12 V outputs (below 20 mV on +12 V outputs, while on the reviewed power supply noise level at +12 V outputs were around 50 mV during test number five). But the results were not bad at all: 50.2 mV at +12V1 input from our load tester, 51.8 mV at +12V2 input from our load tester, 13.2 mV at +5 V and 9.4 mV at +3.3 V. Just to remember, all values are peak-to-peak voltages and the maximum allowed set by ATX standard is 120 mV for +12 V and 50 mV for +5 V and +3.3 V.

Now let’s see how much power we could pull from this unit keeping it working inside ATX specs.

Overload Tests

Before overloading the power supply we always test to see if the over current protection (OCP) circuit is active and at what level it is configured.

To test this we installed only the main motherboard cable and the two ATX12V connectors to the +12V1 input from our load tester, so the load tester was connected only to the +12V1 rail from the power supply.

We started increasing the current at +12 V up to the limit of our load tester – 33 A – but the power supply didn’t shut down. Since the power supply label says that each rail has a 25 A limit, we wanted to see the power supply shutting down if we pulled more than 25 A from any +12 V rail, what didn’t happen.

When we opened the power supply we could clearly see each virtual rail connected to the monitoring integrated circuit, so on this power supply OCP is probably configured at a value that is higher than 33 A. We don’t like this kind of configuration; we think the OCP should be configured at a value close to what is written on the label.

We reinstalled the power supply to our load tester like it was installed before and starting from test number five (see previous page) we started increasing current being pulled from the 12 V inputs from our load tester.

The maximum we could pull from this unit with it still working inside ATX specs is summarized in the table below.

Input

Maximum

+12V1

22 A (264 W)

+12V2

20 A (240 W)

+5V

8 A (40 W)

+3.3 V

8 A (26.4 W)

+5VSB

2.5 A (12.5 W)

-12 V

0.5 A (6 W)

Total

596.8 W

% Max Load

113.7%

Room Temp.

49.3° C

PSU Temp.

51.1° C

AC Power

703 W

Efficiency

84.9%

See how efficiency was still around 85%, which is fantastic.

The only problem is that above this configuration the power supply would turn on with ripple on the moon. When we pulled even more power voltages were far below their expected values (for example, +12 V output at 10.79 V), so under voltage protection (UVP) would have to enter in action shutting the power supply down, which didn’t happen (probably UVP was configured to shut down the power supply only if voltages reached a lower value – which doesn’t make sense, in our opinion). According to Enermax UVP is set at 9.5 V.

In summary, the power supply didn’t shut down in the case of an overloading situation as it should; the unit kept running providing voltages with extreme high ripple and wrong values. On the other hand, the unit didn’t burn.

With the power supply delivering practically 600 W ripple level at +12V1 was 75.4 mV, at +12V2 was 75.8 mV, at +5 V was 13.6 mV and at +3.3 V was 10 mV.

click to enlargeFigure 19: Noise level at +12V1 with this power supply delivering 596.8 W.

click to enlargeFigure 20: Noise level at +12V2 with this power supply delivering 596.8 W.

click to enlargeFigure 21: Noise level at +5V with this power supply delivering 596.8 W.

Short circuit protection (SCP) worked fine for both +5 V and +12 V lines.

The fan used on this power supply is extremely quiet even when it was running at its full speed. In fact this was the quietest power supply we reviewed to date.

Main Specifications

Enermax PRO82+ 525 W power supply specs include:

ATX12V 2.3

Nominal labeled power: 525 W at 40° C.

Measured maximum power: 596.8 W at 59.3° C.

Labeled efficiency: Between 84% and 88%.

Measured efficiency: Between 85.4% and 90.2% at 115 V.

Active PFC: Yes.

Motherboard Power Connectors: One 24-pin connector and two ATX12V connectors that together form an EPS12V connector.

Video Card Power Connectors: One 6-pin connector and two 6/8-pin connectors.

Peripheral Power Connectors: Six, two cables with three standard peripheral power connectors each.

Floppy Disk Drive Power Connectors: One.

SATA Power Connectors: Seven, one cable with four connectors and another cable with three connectors.

Protections: Over voltage (OVP, not tested), under voltage (UVP, not tested), over current (OCP, tested and not working), over power (OPP, tested and not working), over temperature (OTP, not tested) and short-circuit (SCP, tested and working).

Conclusions

Wow! What a power supply! We could not only deliver its labeled 525 W power at 50° C but also maintained efficiency between 85% and 90% all the time! In fact this is the power supply with the highest efficiency we reviewed so far. Not only that. We could pull almost 600 W from this unit still with 85% efficiency. That is impressive.

Another highlight from this product is its noise level. This was the quieter power supply we reviewed to date.

We were really happy to see that the bad results we got with Enermax Liberty DXX 500 W are a problem with this particular model and not a general problem with Enermax.

The number of connectors that come with this power supply should please even high-end users, with seven SATA power plugs and three connectors for video cards (two of them 6/8 pins).

The only problem with this power supply is its price. Costing around USD 150 in the USA it is too expensive for the average user, even though it is worth every penny, especially on the long run, as you will save money on your electricity bill due to the higher efficiency provided by this product.

If you want to save some money and still want to have a power supply with high efficiency, we recommend Antec EarthWatts 500 W (around USD 90) and Corsair VX450W (around USD 80). This model from Corsair is in fact a 500 W and internally it is identical to Antec EarthWatts 500 W, but comes with just one video card auxiliary power plug.

We could also complain that over power (OPP) and over current (OCP) protections didn’t kick in as we expected, but since this power supply survived to our overload tests without burning we don’t think this is really an issue.

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